Reed switch manufacture |
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| 申请号 | US44320374 | 申请日 | 1974-02-19 | 公开(公告)号 | US3908266A | 公开(公告)日 | 1975-09-30 |
| 申请人 | COMTELCO UK LTD; | 发明人 | HILL JOHN; TURCZANSKI HENRY; | ||||
| 摘要 | The invention relates to a method and apparatus for the encapsulation of a switch contact sub-assembly, in which subassembly at least two contacts are rigidly joined in a desired spatial relationship by a destructible bridging piece, wherein the sub-assembly is inserted into a glass tube continuously purged with inert gas and the tube sealed to the sub-assembly by heating two spaced apart regions thereof followed by removal of surplus tube and, in a further aspect of the invention, destruction of the bridging piece. | ||||||
| 权利要求 | 1. A method of encapsulating a switch contact sub-assembly in which at least two contacts are rigidly but temporarily joined in a desired spatial relationship by at least one fusible and electrically conductive bridging piece, comprising the following steps: 1. inserting the contact sub-assembly into a length of glass tube, the length of the tube being greater than the desired length of the capsule being formed, an end of the contact subassembly protruding from a first end of the tube; 2. holding said contact sub-assembly and tube in co-axial relationship for sealing; 2. holding said contact sub-assembly and tube in co-axial relationship for sealing; 2. holding said sub-assembly and tube in co-axial relationship for sealing by supporting only said first end of said tube and the associated protruding end of said sub-assembly; 2. A method according to claim 1 further including the steps of: cooling said encapsulated sub-assembly; and removing the skirt comprising the length of tube between the second seal and the second end of said tube. 3. A method according to claim 2 wherein said purge gas is provided to the interior of said tube by insertion of the open end of a hypodermic needle into the open end of said tube. 3. introducing a flow of purge gas to the interior of said tube through the unsupported end thereof; 3. Providing a flow of purge gas to the interior of said tube; 4. sealing the first end of the tube to the protruding end of the contact sub-assembly by directing a flame toward the first end while maintaining the flow of purge gas into the tube; 5. hEating the tube whereby contaminants within the tube are flushed away by the purge gas; and 6. forming a second seal by directing a flame toward a region of said tube situtate between the two ends of the tube at a distance from the first end corresponding to the desired length of said capsule and while maintaining the flow of purge gas into the tube. 3. Providing a flow of purge gas to the interior of said tube; 4. sealing the first end of the tube to the protruding end of the contact sub-assembly by directing a flame toward the first end while maintaining the flow of purge gas into the tube; 4. sealing the supported end of said tube to the protruding end of said sub-assembly while maintaining the flow of purge gas into said tube; 4. A method according to claim 3 including a final step of removing any sharp edge of glass by flame polishing. 5. A method according to claim 1 in which the assembly is vertically aligned during each of the method steps. 5. hEating the tube whereby contaminants within the tube are flushed away by the purge gas; and 5. heating the entire length of said tube between the regions being sealed to cause release of contaminants from the interior of said tube for flushing away by said purge gas; and 6. sealing the region of said tube disposed a predetermined distance from the supported end of said tube corresponding to the desired length of said capsule while maintaining the flow of purge gas to thereby complete encapsulation of said sub-assembly. 6. forming a second seal by directing a flame toward a region of said tube situtate between the two ends of the tube at a distance from the first end corresponding to the desired length of said capsule and while maintaining the flow of purge gas into the tube. 6. A method according to claim 1 in which the assembly is rotated during the sealing operation to provide for uniform heating of said tube. 7. A method according to claim 1 in which the assembly of said tube and contact sub-assembly is heated by a flame along the length of said tube between the sealing regions thereof prior to the sealing operation. 8. A method according to claim 1 in which the cooling rate of the sealed region of the assembly after sealing is reduced by continued heating thereof for a predetermined length of time to thereby minimize thermal stress of said assembly. 9. A method according to claim 1 including the further step of passing a pulse of electrical energy through the bridging piece which is thereby disintegrated to provide electrically spaced switch contacts within said tube. 10. A method of encapsulating an electrical sub-assembly in which at least two conductive elements are rigidly but temporarily joined in a desired spatial relationship by at least one fusible and electrically conductive bridging piece, comprising the steps of: |
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